Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Origin, dynamics, and chemical evolution of garnet-bearing leucogranitic magma, Eastern Desert of Egypt: Controls on the rare-metal enrichment in the A-type magmatism
Stockholm University, Faculty of Science, Department of Geological Sciences.ORCID iD: 0000-0003-0498-1849
Show others and affiliations
Number of Authors: 52023 (English)In: Chemie der Erde, ISSN 0009-2819, E-ISSN 1611-5864, Vol. 83, no 4, article id 126025Article in journal (Refereed) Published
Abstract [en]

Egypt hosts numerous rare-metal granites, i.e., highly evolved granites enriched in rare metals (Ta, Nb, Be, Sn, Zr, Th, and REE). However, the processes involved in the rare-metal enrichment are not fully understood. We present new data on the textural characteristics and chemical composition of rare-metal mineralization associated with microgranite dikes in the Ras Abdah area of the Egyptian Eastern Desert. These dikes are garnet-bearing leucogranites (GLG) composed of perthitic alkali-feldspars and quartz. When compared to other Egyptian A-type granites, microgranite dikes are alkaline rocks with particularly higher HREE contents. Zircon, huttonite, fergusonite (Y), and Fe-Ti-Zn oxides (magnetite, Zn-bearing ilmenite and pyrophanite) are largely associated with the altered domains, which are also enriched in Nb, Zr, Y, Ta, Th, and REE. However, similarities between the chondrite-normalized REE patterns of the altered and unaltered domains of the GLG dikes favor the hypothesis of a unique magmatic signature. Moreover, the chemical and textural features of rare-metal minerals indicate that the alteration of primary minerals was caused by deuteric fluids or aqueous residual melt exsolved from the parental granitic magma (autometasomatism). Garnet compositions are rich in the spessartine component (up to 84 %), which is typical of garnet in highly evolved pegmatitic rocks. Furthermore, garnet exhibits no major element zoning but shows chemical fluctuations in trace element concentrations, suggesting correspondingly abrupt changes in melt composition due to sequential magma pulsing. This magma emplacement may cause crystal nucleation and oscillatory crystallization followed by magmatic segregation. Overall, parental magma type, dike injection, and magmatic-hydrothermal processes all play a role in the unusual enrichments of rare metals.

Place, publisher, year, edition, pages
2023. Vol. 83, no 4, article id 126025
Keywords [en]
A-type granite, Garnet, Magma pulsing, Rare-metal mineral, Autometasomatism
National Category
Geology
Identifiers
URN: urn:nbn:se:su:diva-226624DOI: 10.1016/j.chemer.2023.126025ISI: 001149655100001Scopus ID: 2-s2.0-85169055524OAI: oai:DiVA.org:su-226624DiVA, id: diva2:1838213
Available from: 2024-02-15 Created: 2024-02-15 Last updated: 2024-02-15Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Authority records

Pease, Victoria

Search in DiVA

By author/editor
Pease, Victoria
By organisation
Department of Geological Sciences
In the same journal
Chemie der Erde
Geology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 45 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf